I. Field of the Invention
The invention in general relates to suspension systems for vehicles including trailers and trailing vehicles. In particular, the invention relates to torsional suspension systems with nonlinear torsion rods and a rotatable oscillating torque hub which is capable of limiting the rotational or torsional movement of the torsion rods.
II. Description of the Prior Art
Torsional axles have long been used to accomplish a means of suspension. In prior applications, various individuals have used straight or linear torsion rods to absorb the various forces which are imparted while travelling. It has been recognized, however, that the rotational movement of torsion rods within the torsion assembly must be limited to avoid overrotation and breakage of the rods. See for example, U.S. Pat. No. 4,744,588 issued to Charles E. Wharton (assigned to TLW, Inc.) and U.S. Pat. No. 4,723,790 issued to Charles E. Wharton (assigned to TLW, Inc.).
The major problem with linear torsion rods is that they are subject to breakage unless a limiter is used. Linear torsion rods also require use of a rotatable torque hub and a fixed counter-torque hub. In this configuration, the torsion bars are held in place by the counter-torque hub and twist when the torque hub rotates. Overrotation of the torque hub often results in breakage of one or more torsion rods. When a limiter is used to prevent this problem, however, the limiter imparts great force against the axle tubing and, in heavy load situations, may damage the axle tubing, possibly rendering the axle tubing not repairable. The current invention solves those problems by using a torque hub which is capable of limiting the rotational motion of the torque rods without imparting any force directed on the axle tubing.
Another problem with conventional torsional axle designs using linear torsion rods is that the torsion suspension unit must be fairly large to properly absorb the torsional forces. These conventional designs usually employ lengthy torsion rods and require a counter-torque hub, all of which adds to the size, weight and cost of such axle designs. The present invention, with its curved or non-linear torsion rods, eliminates the need for a counter-torque hub and substantially reduces the size, weight and cost of the overall torsion suspension unit. This provides substantial advantages in manufacturing, production and transportation of these units. In addition, roadside repair becomes feasible because the torsional suspension unit is easily removed and torsion rods are easily replaced.